> Why are you so sure that IQ isn't just a useful fiction that masks a large number of underlying factors that we don't fully understand? Why are you so sure that it is the best predictor of success in these fields. Perhaps other traits are equal or better predictors of success in a particular field, like tenaciousness, or conscientiousness, and perhaps IQ doesn't matter as much if one of those aren't present.

Because the study of human intelligence is a well established scientific discipline with a lot of well-regarded research that replicates and provides explanations of real world phenomena. And it all points to there being this (not yet fully understood) thing called g that is the strongest known predictor of tons of things related to life outcomes.

Here's a blog post by Razib Kahn about an episode of his podcast, The Insight, with guest Stuart Ritchie, a researcher in human intelligence. The podcast episode is a good start.

https://www.gnxp.com/WordPress/2018/04/11/the-insight-episod...

Thanks for the reference.

FWIW, from the Wikipedia page[1] for g:

"However, critics of g have contended that an emphasis on g is misplaced and entails a devaluation of other important abilities, as well as supporting an unrealistic reified view of human intelligence. "

Interesting discussion all around.

1. https://en.wikipedia.org/wiki/G_factor_(psychometrics)